Study Of One Cycle Controlled Single Phase Power Quality Conditioner

The serious pollution of the electric network is produced and the burdens of the electric network are enhanced along with the wide application of a large number of non-linear and impact devices. The power quality is depriving constantly. Improving and guaranteeing the power quality, especially guaranteeing the power quality of the sensitive users has already become the urgent important subject to be solved by the domestic and international electric field. The power quality conditioner (PQC) that is also called custom power is composed of a serial inverter and a parallel inverter. It can compensate the current and voltage at the same time, and offer the steady voltage of power supply to user while improving power factor of the electric network. It is a device that can improve the power quality of electric network comprehensively.The single-phase power quality conditioner, which is against individual user is mainly studied in this thesis. The one-cycle control technology is combined with single-phase power quality conditioner in this thesis. The operation principle and operation mechanism of single-phase power quality conditioner based on one cycle control are also analyzed detailed. Then experiment study is done in the thesis.At first the operation principles of single phase full bridge PQC and half bridge PQC are analyzed, and corresponding control equation of one cycle control of single phase PQC is deduced and detailed simulation studies are done. The results indicate that the power quality conditioner can compensate power quality effectively stabilize the power supply voltage of load and improve power factor of the source when the heavy fluctuation and harmony waves generate in source voltage.In the simulation study of single phase PQC, the dc offset current in source current can be observed and the global stability still has not realized. So the reasons of dc offset current and instability of system are found by analyzing the control theory in the thesis. The control schemes of dc offset suppression and realizing global stability are proposed. The simulation results verify the correctness and effectiveness of the proposed methods by static simulation and dynamic simulation.Secondly, the performance of main circuit in different conditions is detailed analyzed in the thesis. The capacity of the serial inverter, the parallel inverter and the source is different with the two main circuits in different conditions. The expression formulas of the capacity of the serial inverter, the parallel inverter and the source in...